In addition to looking for a second headquarters, Amazon reportedly is now looking for 1 million square feet of office space in Boston.

According to the Boston Globe, the Seattle-based company is in negotiations with a developer in the city's Seaport District to lease an entire office building — possibly two.

The Globe reports that the retail behemoth employs more than 1,000 people in Boston and Cambridge and already has offices open or under construction in Kendall Square, the Back Bay and Fort Point. The company expects to double that number in the next few years.

The search for the Seaport space reportedly began months before Amazon announced in September that it was seeking a second headquarters. Boston, has emerged as a top contender for the headquarters, as Amazon promises to bring 50,000 new jobs to the area.

Amazon has zeroed in on Seaport Square, a planned complex of office buildings and housing along and near Seaport Boulevard. Chestnut Hill-based WS Development recently won city permits for those buildings. According to the Globe, Amazon and WS Development are negotiat about 500,000 square feet of office space, with an option to lease a second building of about equal size later on.

A spokesperson for the company told the Globe she had no information on any growth plans in the Seaport District.

Boston City Hall and WS Development declined comment.